Patrick Waldron, a spokesperson for Canadian National, said part of the investigation by the Federal Railroad Administration includes why the two crew members weren't on board at the time the train derailed.

"They are investigating why the men left the locomotive, but we do know they activated the emergency brakes before the train derailed," said Patrick Waldron, a CN spokesperson.

Waldron couldn't specify whether the crew members jumped or fell from the moving locomotive.

"Safety is our number one priority," Mike England with the The Federal Railroad Administration wrote in an e-mail. "The FRA has investigators on site in Two Harbors. We are conducting a thorough investigation that will examine all factors contributing to this accident."

Waldron said the rail line on which the train derailed was repaired over the weekend.